The invention relates to a method for determining the relative position of an object in space in six spatial degrees of freedom and to an optical input system for generating digital position data, which represent the relative position of the input device in space in six spatial degrees of freedom relative to an optical detection apparatus.
By way of example, optical input systems can be employed to control functions of connected terminals. By way of example, an actuatable terminal can be a personal computer (PC) or a games console or a television set or the like.
There are numerous input systems which can be used in conjunction with a computer in order to control functions of the computer. A conventional mouse, which can be moved by the user by hand on a planar pad and which communicates to a computer by means of a wire or wirelessly using a radio link, for example renders it possible to control the location of a computer-generated mouse pointer on the screen of the computer system. Different actions in the operating system or an application can be triggered by actuating a mouse button.
There are many applications where an input with more than two degrees of freedom is advantageous or required for the control thereof. By way of example, it is desirable for many computer games or graphics applications to have available an input system which enables the control of computer-generated objects in more than two dimensions, in particular in all six spatial degrees of freedom (6D input system). A 6D input system generally has a hand-held input device, which is held using one hand by a user and can both be moved in a translational manner in space and be pivoted or rotated in different directions. By using a 6D input system, it should be possible to determine both the location of the input device in space and the orientation of the input device in space with a speed and accuracy sufficient for the control object such that movements of the input device can be employed to control the terminal.
U.S. Pat. No. 6,417,836 B1 describes a method for determining the relative position of an input device in space in six spatial degrees of freedom. The input device has a grip, at the upper end of which a plate is applied, which carries a marking pattern with five luminous markings, arranged in coplanar fashion, in the form of LEDs. This input device is moved within the detection region of a camera in such a way that the markings are imaged or projected onto assigned image locations of the two-dimensional sensor surface of the camera. From the associated image coordinates, the relative position of the marking pattern is determined with the aid of a computer-numerical evaluation method. To this end, video signals from the camera are transmitted to a computer separate from the camera, the computational power of which computer is sufficient to perform the evaluation method. During the evaluation, a label is assigned to each of the markings in order to enable differentiation of the markings from one another. In one variant, this differentiation of the markings is achieved by virtue of the latter having different colors. In another variant, the labeling is achieved by virtue of the movement of images of the markings being tracked over a number of successive images. Another variant for identifying or labeling the markings employs geometric relationships between the five markings lying in a common plane.